JP2005201117A - Variable valve system failure diagnosing device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve certainty of evacuation travel when a failure occurs in a variable valve system of an internal combustion engine. <P>SOLUTION: The abnormality diagnosis (S104) of a slide sensor of the variable valve system is performed when the valve operating angle is in an initial state ("YES" in S102). The initial state is set to a valve characteristic state having a maximum valve operating angle. The maximum valve operating angle corresponds to an evacuation travelable region, and engine start and evacuation travel operation are allowed. Even when adjustment of the valve operating angle by rotation of a spiral cam is difficult due to a failure of the slide sensor ("YES" in S106), the evacuation travel is allowed only by keeping the initial state by keeping control (S108). Thus, the certainty of the evacuation travel can be improved when the failure occurs in the variable valve system. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a variable valve mechanism control device that detects an adjustment state of a variable valve mechanism that adjusts valve characteristics by a sensor and drives an actuator provided in the variable valve mechanism based on a detection value of the sensor.

2. Description of the Related Art A variable valve mechanism that adjusts an intake air amount by making a valve operating angle variable to improve fuel efficiency in an internal combustion engine is known. In such a variable valve mechanism, an actuator for driving the mechanism and a sensor for detecting the adjustment state of the valve working angle are provided. However, if these actuators or sensors fail, the valve operating angle cannot be adjusted, and the internal combustion engine may stop due to a decrease in the intake air amount, making it impossible to retreat. Therefore, a technique for diagnosing these failures and changing the valve operating angle to a state in which retreat travel is possible when the failure is determined is proposed. For example, when the sensor is abnormal, a technique has been proposed in which the valve operating angle is estimated based on the operating state of the internal combustion engine, and the actuator of the variable valve mechanism is driven so that the valve operating angle becomes a target value for failure. (For example, refer to Patent Document 1).
JP 2002-314329 A (page 6-7, FIG. 11)

  However, since the valve operating angle is estimated based on the operating state of the internal combustion engine in the above-described prior art, it is necessary that the internal combustion engine is actually in the operating state when the sensor failure is detected, and the point in time when the sensor is detected to be in failure. When the internal combustion engine is stopped or when the internal combustion engine is in transition, the valve operating angle cannot be moved to the target value. For this reason, there is a high possibility that starting becomes difficult or stable engine operation cannot be performed continuously, and retreat traveling cannot be performed.

  Furthermore, if the actuator, not the sensor, fails and the valve operating angle cannot be changed, it is impossible to increase the engine output by increasing the valve operating angle, and retreat travel is impossible. In addition, depending on the configuration of the variable valve mechanism, the force received from the valve side acts in the direction of reducing the valve operating angle. However, if the actuator fails, it will not be able to counter this force, so the internal combustion engine will stop. Therefore, after that, starting and retreating are impossible.

  An object of the present invention is to increase the certainty of retreat travel when a failure occurs in a variable valve mechanism.

In the following, means for achieving the above object and its effects are described.
The variable valve mechanism failure diagnosis apparatus for an internal combustion engine according to claim 1 provides a control shaft for adjusting one or both of a valve lift amount and a valve operating angle of the internal combustion engine via a control shaft position adjustment mechanism. A failure diagnosis device for a variable valve mechanism that is driven by an actuator, detects a valve characteristic of the control shaft by a sensor, and controls the actuator based on a detection value of the sensor. Failure diagnosis means for executing failure diagnosis of the variable valve mechanism when it is determined that the valve characteristic exists in the retreatable travelable region set within the adjustment range of the valve characteristics; and the variable valve actuation by the failure diagnosis means When it is diagnosed that the mechanism is faulty, the valve characteristics can be Holding control for lifting, or characterized by comprising a valve state holding means for executing a hold control for holding the retracted travelable in greater state than the region.

  Thus, the failure detection timing by the failure diagnosis means is when the valve characteristic exists in the retreat travelable region. Therefore, when it is determined that the sensor or actuator of the variable valve mechanism is abnormal at this timing, the holding control is executed by the valve state holding means.

  The holding control is a process of holding the valve characteristic in a state where it is in the retreatable travelable region or holding it in a state larger than the retreatable travelable region. As described above, the failure diagnosis timing is when the valve characteristic exists in the retractable travelable region. Therefore, adjustment of the valve characteristic is not necessary when the valve characteristic is maintained in the retractable travelable region as the holding control. Therefore, the holding control can be performed even if the actuator or the sensor is out of order.

  When the sensor is broken or when the actuator is broken only in the direction of decreasing the valve characteristic, it is possible to make the valve characteristic larger than the current retreatable region. Therefore, as the holding control, the valve characteristic may be held in a state larger than the retreatable travel area, and the retreat travel of the internal combustion engine can be sufficiently dealt with.

  Furthermore, when failure diagnosis is performed, the valve characteristics may be larger than the retreat travelable region where the valve characteristics existed at the start of diagnosis. However, even if the valve characteristic is maintained when such a state is reached, it is possible to sufficiently cope with the retreat travel of the internal combustion engine.

  In this way, failure diagnosis is performed when valve characteristics exist in the retractable travel area, so that even if a failure is determined, the valve characteristics are reliably maintained in a retractable travel area or larger than the retractable travel area. can do.

  Therefore, even if the internal combustion engine is stopped when it is determined that there is a failure, the engine can be started reliably and can be evacuated. In addition, even when the operating state of the internal combustion engine is in a transient state, the valve characteristic can be maintained in a sufficiently large state before the valve characteristic becomes such that the internal combustion engine stops, so that a situation in which retreat traveling cannot be performed is prevented.

In this way, it is possible to improve the certainty of retreat travel when a failure occurs in the variable valve mechanism.
The variable valve mechanism failure diagnosis apparatus for an internal combustion engine according to claim 2 is characterized in that, in claim 1, the failure diagnosis means determines failure of the sensor.

  In this way, the presence or absence of a sensor failure is executed when the valve characteristic exists in the retreatable area, so that even if it becomes clear that the valve characteristic cannot be adjusted normally after that, it will be sure after the failure judgment. Therefore, it is possible to maintain the valve characteristics that enable retreat travel. Accordingly, it is possible to improve the certainty of the retreat travel when a failure occurs in the variable valve mechanism.

The variable valve mechanism failure diagnosis apparatus for an internal combustion engine according to claim 3 is characterized in that, in claim 1, the failure diagnosis means determines failure of the actuator.
In this way, whether or not there is a failure in the actuator is executed when the valve characteristic exists in the evacuation travelable region. Therefore, even if it becomes clear that the valve characteristic cannot be adjusted normally after that, it is ensured after the failure judgment. Therefore, it is possible to maintain the valve characteristics that enable retreat travel. Accordingly, it is possible to improve the certainty of the retreat travel when a failure occurs in the variable valve mechanism.

  The variable valve mechanism failure diagnosis device for an internal combustion engine according to claim 4, wherein the control shaft position adjusting mechanism is at least in a state where the valve characteristic exists in the retreat travelable region. The valve characteristics can be maintained without depending on the driving force of the actuator, and the valve state holding means executes the holding control by stopping the driving force output from the driving force supply source to the actuator. It is characterized by.

  When the control shaft position adjusting mechanism is configured as described above, the holding control may be such that the driving force output from the driving force supply source to the actuator is stopped. As a result, even if either the sensor or the actuator is out of order, it is possible to maintain the valve characteristics that allow the retreat travel without consuming drive energy after the failure determination. Accordingly, it is possible to improve the certainty of the retreat travel when a failure occurs in the variable valve mechanism.

  The variable valve mechanism failure diagnosis apparatus for an internal combustion engine according to claim 5 is characterized in that, in claim 2, the valve state holding means has a valve characteristic that increases a driving force output from a driving force supply source to the actuator. The holding control is executed by switching the output state to a lower level than the driving force output in the normal state.

  Depending on the control shaft position adjusting mechanism, the valve characteristics may gradually decrease due to the force received by the control shaft from the valve side. Further, even if the control shaft position adjusting mechanism has a configuration in which the valve characteristic can be maintained without depending on the driving force of the actuator at least in a state where the valve characteristic exists in the retreatable travelable region, the control shaft position adjustment mechanism is caused by vibration during operation of the internal combustion engine. The valve characteristics may deviate from the retreatable region.

  Therefore, as the holding control, the driving force output from the driving force supply source to the actuator is set to a direction in which the valve characteristic is increased, and the output state is switched to a lower level than the driving force output in the normal state. Accordingly, the valve characteristic may be maintained in a state where the valve characteristic is in the retreat travelable region or in a state where the valve characteristic is greater than the retreat travelable region.

  Furthermore, since the driving force output from the driving force supply source is switched to an output state at a lower level than the driving force output at the normal time, less energy is required for holding control. Further, this prevents the control shaft position adjusting mechanism from moving the control shaft or the member interlocked with the control shaft at high speed. Therefore, even when the control shaft moves to the end, the internal member of the variable valve mechanism, the control shaft position adjusting mechanism, the control shaft, or the like is prevented from colliding with the stopper or the like at high speed. For this reason, the durability of the variable valve mechanism can be improved, and the driver can be prevented from feeling uncomfortable due to the impact sound.

  The variable valve mechanism failure diagnosis apparatus for an internal combustion engine according to claim 6, wherein the variable valve mechanism includes a spiral cam as the control shaft position adjusting mechanism, and the spiral cam Is a mechanism for adjusting the valve characteristic of the internal combustion engine by moving the control shaft in the axial direction by rotating the actuator by the actuator, and the retractable travel region is set to an adjustment state in which the valve characteristic is maximized, The spiral cam has an arc surface having a cam rotation axis as an axis on a cam surface corresponding to the retractable travelable region.

  An example of the control shaft position adjusting mechanism is a configuration using the spiral cam. As a result, when the spiral cam is rotated by the actuator, the cam surface gradually increases, and when it is reversed, the cam surface decreases. For this reason, the position adjustment of the control shaft can be easily performed by the rotary actuator.

  Furthermore, since the spiral cam has an arc surface with the cam rotation axis as an axis on the cam surface corresponding to the retractable travel area, when the control shaft for adjusting the valve characteristics is adjusted on this arc surface, Even if axial force is generated, the spiral cam does not generate any rotational force in any direction.

  Accordingly, when the valve characteristic is in the retreatable travel region, it is not necessary to cause the actuator to generate a driving force, and the driving force may be smaller than that during normal driving in order to prevent deviation due to vibration of the internal combustion engine. Accordingly, holding control can be performed with little or no driving energy.

  The variable valve mechanism failure diagnosis device for an internal combustion engine according to claim 7, wherein the variable valve mechanism includes a worm gear as the control shaft position adjusting mechanism, and the worm gear is used as the control shaft position adjusting mechanism. The mechanism is characterized in that the valve characteristic of the internal combustion engine is adjusted by moving the control shaft in the axial direction by rotating the driven gear by rotating with an actuator.

  The worm gear can be used as the control shaft position adjusting mechanism. Thus, when the worm gear is rotated by the actuator, the control shaft can be moved in the axial direction via the driven gear rotated by the worm gear, and when the worm gear is rotated in the reverse direction, the control shaft can be moved in the reverse direction. In this way, the position of the control shaft can be easily adjusted by the actuator.

  Further, since the worm gear is used, it is possible to prevent the worm gear side from rotating due to the axial force generated in the control shaft. Accordingly, when the valve characteristic is in the retreatable travel region, it is not necessary to cause the actuator to generate a driving force, and the driving force may be smaller than that during normal driving in order to prevent deviation due to vibration of the internal combustion engine. Accordingly, holding control can be performed with little or no driving energy.

  Furthermore, the rotation of the worm gear can be stopped without causing the actuator to generate a driving force in any state of the valve characteristics. Therefore, the degree of freedom for setting the retreatable travel area increases and the types of engines that can be applied increase.

  The variable valve mechanism failure diagnosis apparatus for an internal combustion engine according to claim 8, wherein the variable valve mechanism includes a spiral cam as the control shaft position adjustment mechanism, and the spiral cam is rotated by the actuator. By moving the control shaft in the axial direction, the valve characteristic of the internal combustion engine is adjusted, the retractable travel region is set to an adjustment state in which the valve characteristic is maximized, and the spiral cam is The cam surface corresponding to the retreatable travel area has an arc surface with the cam rotation axis as an axis, and the failure diagnosis means determines the failure of the actuator by driving the actuator in a direction in which the valve characteristic increases. It is characterized by doing.

  When the spiral cam is used as the control shaft position adjusting mechanism, the failure determination may be performed by driving the actuator in a direction in which the valve characteristic is increased.

  The spiral cam has the maximum valve characteristic in the retreatable travel region, and the valve characteristic is constant in the retreat travelable region. Therefore, even if the actuator is driven in such a way that the valve characteristic becomes larger in the retreat travelable region, the valve characteristic does not actually change and is kept constant. Finally, the adjustment limit is reached, and the actuator stops even if the driving force is supplied.

  When the actuator is normally driven as described above and reaches the adjustment limit, some change occurs in the state of the driving force or the driving force supply source side. Therefore, when this change cannot be captured, it can be determined that the actuator has failed.

In the case of a sensor that detects the valve characteristics by directly measuring the drive amount of the actuator, the presence or absence of the actuator failure may be diagnosed from the change in the sensor output.
Further, in such a failure diagnosis process, the valve characteristic remains constant, so that failure diagnosis can be performed without affecting the combustibility.

  A variable valve mechanism failure diagnosis apparatus for an internal combustion engine according to claim 9, wherein the variable valve mechanism includes a worm gear as the control shaft position adjusting mechanism, and the worm gear is rotated by the actuator. The mechanism is a mechanism that adjusts the valve characteristic of the internal combustion engine by rotating the driven gear in the axial direction by rotating the control shaft, and the failure diagnosis unit drives the actuator toward a direction in which the valve characteristic increases. Thus, the failure of the actuator is determined.

  When the worm gear is used as the control shaft position adjusting mechanism, the failure determination may be performed by driving the actuator toward a direction where the valve characteristic becomes larger.

  In the case of this worm gear, the retreat travelable region can be set to the maximum valve characteristic, but depending on the internal combustion engine, the valve characteristic position may be set to be smaller than the maximum valve characteristic.

  When the retreat travelable region is set to the maximum valve characteristic, if the actuator is normally driven as described in claim 8, immediately after the actuator is driven to increase the valve characteristic, Come to the adjustment limit. As a result, some change occurs before and after reaching the adjustment limit on the state of the driving force or on the driving force supply source side. Therefore, when this change cannot be captured, it can be determined that the actuator has failed.

  When the retreat travelable region is set to a valve characteristic smaller than the maximum valve characteristic, if the actuator is driven in a direction in which the valve characteristic becomes larger, if it is normal, it will appear in the detection value of the sensor. However, if no change in the valve characteristic appears in the detection value of this sensor, it can be determined that the actuator has failed.

  Further, after such a failure diagnosis process, the valve characteristic is maintained in a state where the valve characteristic is in the retractable travelable area or in a state where the valve characteristic is larger than that in the retractable travelable area. Therefore, even if the internal combustion engine is stopped, the engine can be started reliably and can be evacuated. Further, even during operation of the internal combustion engine, the valve characteristic can be maintained before the valve characteristic becomes such that the internal combustion engine stops.

  In this way, it is possible to improve the certainty of retreat travel when a failure occurs in the variable valve mechanism. Further, as described in the seventh aspect, the degree of freedom in setting the retreat travelable region is high.

  The variable valve mechanism failure diagnosis device for an internal combustion engine according to claim 10, wherein the failure diagnosis means is in an output state at a level lower than the driving force output during normal control of the internal combustion engine. The actuator is driven to increase the valve characteristics.

  In this way, the drive of the actuator to the larger valve characteristics performed for failure diagnosis is a normal driving force output, that is, a low level output state compared to the valve characteristics adjustment during normal control of the internal combustion engine Is done. For this reason, even if the adjustment limit is reached, the momentum at the time of collision is small, so that the durability of the variable valve mechanism can be improved and the driver can be prevented from feeling uncomfortable due to the impact sound.

  12. The variable valve mechanism failure diagnosis apparatus for an internal combustion engine according to claim 11, wherein the failure diagnosis means drives the actuator to increase the valve characteristics. If the valve characteristic is normal, the actuator is driven in such a way that the valve characteristic becomes smaller, thereby determining a failure of the actuator when the valve characteristic is made smaller.

  The failure of the actuator is not abnormal for driving in one direction, but there is a failure that cannot be driven in the opposite direction. Therefore, if the actuator has failed in the direction of increasing the valve characteristics, it will not be possible to increase the valve characteristics after determining that the actuator has not failed by reducing the valve characteristics first. There is a possibility that it will remain off the smaller possible area. Furthermore, the valve characteristics may gradually decrease due to this.

  However, in this case, as a failure diagnosis, the driving toward the one where the valve characteristic becomes large is first performed. As a result, if the valve characteristic becomes larger and a failure occurs, the valve characteristic is maintained in a state where the valve characteristic is in the retreat travelable area by immediately holding control, so that starting and retreat travel are possible.

  Then, when it is determined that there is no failure when the valve characteristic is increased, the actuator is driven to the direction where the valve characteristic is decreased only when it is determined that there is no failure, thereby determining the failure of the actuator when the valve characteristic is decreased. Even if a failure is found by this determination, the valve characteristic can be increased so that the valve characteristic can be increased, so that the valve characteristic can be immediately increased so that the retreat travelable region or more can be achieved.

This can increase the certainty of retreat travel when a failure occurs in the variable valve mechanism.
A variable valve mechanism failure diagnosis apparatus for an internal combustion engine according to claim 12, wherein a control shaft that adjusts one or both of valve characteristics of a valve lift amount and a valve working angle of the internal combustion engine is provided via a control shaft position adjustment mechanism. A failure diagnosis device for a variable valve mechanism that is driven by an actuator, detects a valve characteristic of the control shaft by a sensor, and controls the actuator based on a detection value of the sensor. Failure diagnosis means for executing failure diagnosis of the variable valve mechanism when it is determined that the valve characteristic exists in the retreatable travelable region set within the adjustment range of the valve characteristics; and the variable valve actuation by the failure diagnosis means When the mechanism is diagnosed as malfunctioning, the valve characteristics are in the evacuable travel area Valve state holding means for performing holding control for holding or holding control for holding in a state in which the valve characteristic is larger than the retreat travelable region, and the variable valve mechanism includes a worm gear as the control shaft position adjusting mechanism. A mechanism for adjusting the valve characteristic of the internal combustion engine by rotating the driven shaft by rotating the worm gear by the actuator, and the retractable travelable region is retracted The region is set to a region larger than the lower limit of the adjustment position of the valve characteristic that can be traveled, and the failure diagnosis means determines the failure of the actuator by driving the actuator toward a smaller valve characteristic. Features.

  When the worm gear is used as the control shaft position adjustment mechanism in this way, if the retractable travelable region is set to a region larger than the lower limit of the adjustment position of the valve characteristic that can be retracted, The actuator may be driven so that the valve characteristic becomes smaller.

  If the actuator is normal, it will appear in the detected value of the sensor if the actuator is driven in such a way that the valve characteristic is reduced to the adjustment position where the detected value of the sensor is expected to change. However, when the valve characteristic change does not appear in the detection value of the sensor, it can be determined that the actuator has failed.

  Furthermore, the retreat travelable region is set to an adjustment position that is larger than the lower limit of the adjustment position of the valve characteristic that can actually retreat travel. For this reason, even after failure diagnosis processing by reducing the valve characteristic, the valve characteristic can be maintained in a valve characteristic state that can be effectively retreated. Therefore, even if the internal combustion engine is stopped, the engine can be started reliably and can be evacuated. Further, even during operation of the internal combustion engine, the valve characteristic can be maintained before the valve characteristic becomes such that the internal combustion engine stops.

  In this way, it is possible to improve the certainty of retreat travel when a failure occurs in the variable valve mechanism. Further, as described in the seventh aspect, the degree of freedom in setting the retreat travelable region is high.

  The variable valve mechanism failure diagnosis device for an internal combustion engine according to claim 13, wherein the failure diagnosis means is configured to detect a valve when the actuator is driven normally to reduce the valve characteristic. It is characterized in that a failure of the actuator is determined when the valve characteristic is increased by driving the actuator in a direction in which the characteristic is increased.

  The failure of the actuator is not abnormal for driving in one direction, but there is a failure that cannot be driven in the opposite direction. Therefore, if the actuator has failed in the direction of decreasing the valve characteristics, if it is determined that the actuator is not malfunctioning by increasing the valve characteristics first, it will not be possible to reduce the valve characteristics, and retreating will occur. There is a possibility that it will remain off the larger area from the possible area. However, in this case, since the valve characteristic is ensured to be larger than the retreat travelable region, starting and retreat travel are possible.

  Therefore, in this case, the actuator is diagnosed by driving it in the direction of decreasing the valve characteristics. If it is determined that there is no failure in this fault diagnosis, the actuator is diagnosed by driving in the direction of increasing the valve characteristics. May be performed.

This can increase the certainty of the retreat travel when a failure occurs in the variable valve mechanism.
In the variable valve mechanism failure diagnosis apparatus for an internal combustion engine according to claim 14, in any one of claims 1 to 13, when the internal combustion engine is stopped, the valve characteristic is set to an initial state set for starting. Provided with a starting valve characteristic setting means for driving the actuator, and the initial state is set in the retractable travelable region.

  By providing the starting valve characteristic setting means, the valve characteristic is set in the retreatable travelable region at the time of starting. Therefore, failure diagnosis can be executed before starting the internal combustion engine at the time of starting. Moreover, if it is determined that there is a failure, at least the initial state can be maintained, or the valve characteristics higher than the initial state can be maintained. Accordingly, it is possible to improve the certainty of the retreat travel when a failure occurs in the variable valve mechanism.

[Embodiment 1]
FIG. 1 shows a schematic configuration diagram of a gasoline engine (hereinafter abbreviated as “engine”) 2 as an internal combustion engine mounted on a vehicle and an electronic control unit (hereinafter referred to as “ECU”) 4 as a control device. ing. The engine 2 is a multi-cylinder engine, here, a 4-cylinder engine, and a variable valve system for one cylinder among them is shown in the longitudinal sectional view of FIG. Each cylinder is provided with two intake valves 2a and two exhaust valves 2b, and is configured as a four-valve engine. The number of cylinders may be 6 cylinders or 8 cylinders, and may be a 2-valve engine or a 5-valve engine.

  The output of the engine 2 is finally transmitted as traveling driving force to the wheels via the transmission. The engine 2 has a combustion chamber 12 defined by a piston 6, a cylinder block 8 and a cylinder head 10. The cylinder head 10 is provided with a spark plug 14 and a fuel injection valve 16 (FIG. 1) for directly injecting fuel into the combustion chamber 12 in order to ignite the air-fuel mixture in the combustion chamber 12. The fuel injection valve 16 may inject fuel into the intake port 18 connected to the combustion chamber 12.

  The intake port 18 is opened and closed by driving the intake valve 2 a, and each intake passage 20 connected to the intake port 18 is connected to a surge tank 22. A throttle valve 26 whose opening (throttle opening TA) is adjusted by a motor 24 is provided upstream of the surge tank 22. The throttle valve 26 is normally almost fully open, but depending on the state of the engine 2, the throttle opening TA may be controlled to adjust the intake air amount GA. For example, as described later, when a failure of the variable valve mechanism 54 is detected and the valve operating angle of the intake valve 2a is held in the initial state, the retreat travel is enabled by adjusting the throttle opening degree TA. The throttle opening degree TA is detected by the throttle opening degree sensor 28 and read into the ECU 4. The intake air amount GA is detected by an intake air amount sensor 30 provided on the upstream side of the throttle valve 26, and the intake air temperature THA is detected by an intake air temperature sensor 32 provided on the upstream side of the throttle valve 26 and is read into the ECU 4. ing.

  The exhaust port 34 connected to the combustion chamber 12 is opened and closed by driving the exhaust valve 2b. An exhaust purification catalytic converter 38 is disposed in the middle of the exhaust passage 36 connected to the exhaust port 34. An air-fuel ratio AF is detected on the basis of the exhaust component in the exhaust passage 36 by an air-fuel ratio sensor 40 provided in the exhaust passage 36 upstream of the exhaust purification catalytic converter 38 and is read into the ECU 4.

  The ECU 4 is an engine control circuit configured mainly with a digital computer. In addition to the throttle opening sensor 28, the intake air amount sensor 30, the intake air temperature sensor 32, and the air-fuel ratio sensor 40, the ECU 4 inputs signals from sensors that detect the operating state of the engine 2. That is, an accelerator opening sensor 44 that detects the amount of depression of the accelerator pedal 42 (accelerator opening ACCP), an engine speed sensor 46 that detects the engine speed NE from the rotation of the crankshaft 6a, and a reference crank based on the rotation of the intake camshaft. A signal is input from a reference crank angle sensor 48 that determines the angle. Signals are also input from a slide sensor 50 for detecting the valve operating angle of the intake valve 2a and a coolant temperature sensor 52 for detecting the engine coolant temperature THW. In addition to the sensors described above, sensors for detecting various data are provided.

  In the present embodiment, the valve lift amount also changes in conjunction with the valve operating angle, so the slide sensor 50 is also a sensor that detects the valve lift amount. Hereinafter, the adjustment and behavior described for the valve operating angle also explain the adjustment and behavior for the valve lift amount.

  The ECU 4 controls the fuel injection timing, the fuel injection amount, the throttle opening TA, and the ignition of the engine 2 according to the control signal for the fuel injection valve 16, the throttle valve motor 24 or the ignition plug 14 based on the detection contents from each sensor described above. Control time etc. as appropriate. Further, the ECU 4 controls the valve operating angle and the valve of the intake valve 2a by a control signal for the variable valve mechanism 54 that adjusts the valve operating angle and the valve timing of the intake valve 2a based on the accelerator opening ACCP and the engine speed NE. The timing is adjusted. Of these, the intake air amount is adjusted mainly by adjusting the valve operating angle.

  The variable valve mechanism 54 includes a valve working angle adjustment mechanism 56 and a valve timing adjustment mechanism 58. The valve working angle adjustment mechanism 56 includes a mediation drive mechanism 60 shown in FIGS. 2 to 5 and a shaft slide mechanism 100 shown in FIG.

  As shown in FIG. 2, the mediation drive mechanism 60 is disposed between a roller rocker arm 62 provided for the intake valve 2a and an intake cam 64a provided on the intake cam shaft 64, and from the intake cam 64a. The intake valve 2a is driven by applying the valve driving force to the roller rocker arm 62.

  As shown in the perspective view of FIG. 3 and the horizontal cutaway perspective view of FIG. 4, the intermediate drive mechanism 60 provided for each cylinder is provided at the input portion 66 provided at the center of the drawing and at one end side of the input portion 66. A first rocking cam 68, a second rocking cam 70 provided on the opposite side of the first rocking cam 68, and a slider gear 72 disposed inside are provided.

  A housing 66a of the input portion 66 forms a space in the axial direction inside, and a helical spline 66b formed in a spiral shape of a right-hand thread is provided in the axial direction on the inner peripheral surface of this space. In addition, two parallel arms 66c and 66d are formed to protrude from the outer peripheral surface of the housing 66a. A roller 66f having a shaft 66e parallel to the axial direction of the housing 66a is rotatably attached to the ends of the arms 66c and 66d. As shown in FIG. 2, the urging force of the spring 66g is applied to the arms 66c and 66d or the housing 66a so that the roller 66f always contacts the intake cam 64a.

  The housing 68a of the first swing cam 68 forms a space in the axial direction inside, and a helical spline 68b formed in a spiral shape of a left-hand screw in the axial direction is provided on the inner peripheral surface of the internal space. One end of the inner space of the housing 68a is covered with a ring-shaped bearing portion 68c having a center hole with a small diameter. Further, a substantially triangular nose 68d protrudes from the outer peripheral surface of the housing 68a. One side of the nose 68d forms a cam surface 68e that curves in a concave shape.

  The housing 70a of the second rocking cam 70 forms a space in the axial direction inside, and a helical spline 70b formed in a spiral shape of a left-hand screw in the axial direction is provided on the inner peripheral surface of the internal space. One end of the internal space of the housing 70a is covered with a ring-shaped bearing portion 70c having a center hole with a small diameter. Further, a substantially triangular nose 70d protrudes from the outer peripheral surface of the housing 70a. One side of the nose 70d forms a cam surface 70e that is concavely curved.

  The first swing cam 68 and the second swing cam 70 are disposed so that the bearing portions 68c and 70c are outside and the end faces are coaxially in contact with the input portion 66 from both sides. As shown in FIG. 3, it has a substantially cylindrical shape having an internal space.

  A slider gear 72 is disposed in the internal space formed by the input unit 66 and the two swing cams 68 and 70. The slider gear 72 has a substantially cylindrical shape, and an input helical spline 72a formed in a spiral shape of a right-hand thread is provided at the center of the outer peripheral surface. On one end side of the input helical spline 72a, a first output helical spline 72c formed in a left-handed spiral shape with a small diameter portion 72b interposed therebetween is provided. On the opposite side of the first output helical spline 72c, a second output helical spline 72e formed in a left-handed spiral shape with a small diameter portion 72d interposed therebetween is provided. The output helical splines 72c and 72e have a smaller outer diameter than the input helical spline 72a.

  A through hole 72f is formed in the slider gear 72 in the central axis direction. As shown in the longitudinal section in FIG. 5, a circumferential groove 72g is formed in the circumferential direction on the inner circumferential surface of the through hole 72f at the position of the input helical spline 72a. The circumferential groove 72g is formed with a pin insertion hole 72h penetrating to the outside in a radial direction at one place.

  A support pipe 80 is slidably disposed in the through hole 72f of the slider gear 72 in the circumferential direction. The support pipe 80 is provided in common with the intermediate drive mechanism 60 for all cylinders. The support pipe 80 has long holes 80a formed in the axial direction at positions corresponding to the respective mediation drive mechanisms 60.

  Further, a control shaft 82 is disposed in the support pipe 80 so as to be slidable in the axial direction. Support holes 82b in the direction perpendicular to the axis are provided at positions corresponding to the long holes 80a of the support pipe 80. By inserting the base end portion of the control pin 82a into the support hole 82b, the control pin 82a is supported so as to protrude in the direction perpendicular to the axis.

  In the state where the control shaft 82 is disposed inside the support pipe 80, the tip of each control pin 82 a passes through the axial long hole 80 a formed in the support pipe 80, and the inner periphery of the slider gear 72. It is inserted into a circumferential groove 72g formed on the surface.

  With such a configuration, each slider gear 72 can move in the axial direction by the movement of the control shaft 82, and the position of the slider gear 72 in each intermediate drive mechanism 60 can be determined by the position control of the control shaft 82. However, since each slider gear 72 is locked to the control pin 82a by the circumferential groove 72g, the slider gear 72 can swing around the axis regardless of the position of the control pin 82a.

  Within the slider gear 72, the input helical spline 72 a is meshed with the helical spline 66 b inside the input unit 66. The first output helical spline 72 c is meshed with the helical spline 68 b inside the first swing cam 68, and the second output helical spline 72 e is meshed with the helical spline 70 b inside the second swing cam 70.

  Each intermediary drive mechanism 60 is attached to the cylinder head 10 in a state where movement in the axial direction is prevented on the bearing portions 68c, 70c side of the swing cams 68, 70. Therefore, even if the control shaft 82 moves the slider gear 72 in the axial direction, the input portion 66 and the swing cams 68 and 70 do not move in the axial direction.

  Therefore, by adjusting the axial movement amount of the slider gear 72 in the internal space of the mediation drive mechanism 60, the input portion 66 and the swing cam 68, by the function of the helical splines 72a, 66b, 72c, 68b, 72e, 70b. The phase difference from 70 can be changed. As a result, the positional relationship between the roller 66f and the noses 68d and 70d can be changed.

  Here, FIG. 6 shows the operating state of the mediation drive mechanism 60 when the control shaft 82 is moved in the L direction (arrows in FIGS. 3 and 4) as much as possible. 6A is when the valve is closed, and FIG. 6B is when the valve is opened. In this case, the relative positional relationship between the roller 66f of the input unit 66 and the noses 68d and 70d of the swing cams 68 and 70 is the closest. Therefore, as shown in FIG. 6B, even if the intake cam 64a pushes down the roller 66f of the input portion 66 to the maximum extent, the push-down amount of the rocker roller 62a by the cam surfaces 68e and 70e of the noses 68d and 70d is minimized. Then, the push-down amount becomes zero. For this reason, the valve operating angle of the intake valve 2a (crank angle width from opening to closing) is zero. Therefore, the intake valve 2a remains closed, and the intake air amount from the intake port 18 into the combustion chamber 12 becomes zero.

  FIG. 7 shows the operating state of the mediation drive mechanism 60 when the control shaft 82 is moved in the maximum H direction (arrows in FIGS. 3 and 4). 7A is when the valve is closed, and FIG. 7B is when the valve is opened. In this case, the relative positional relationship between the roller 66f of the input unit 66 and the noses 68d and 70d of the swing cams 68 and 70 is the farthest. Therefore, as shown in FIG. 7B, when the intake cam 64a pushes down the roller 66f of the input portion 66 to the maximum extent, the push-down amount of the rocker roller 62a by the cam surfaces 68e, 70e of the noses 68d, 70d is maximized. The valve operating angle of the intake valve 2a is maximized. Therefore, unlike the case of FIG. 6, the intake valve 2a opens to the maximum in the intake stroke, and the intake air amount from the intake port 18 into the combustion chamber 12 is also maximized.

  By adjusting the axial position of the control shaft 82, the valve operating angle of the intake valve 2a can be continuously adjusted between the state of FIG. 6 and the state of FIG. Such a continuous adjustment state of the valve working angle is shown in the graph of FIG. The state indicated by MIN in FIG. 8 corresponds to the case of FIG. 6, and the intake valve 2a does not open even in the intake stroke. The state indicated by MAX in FIG. 8 corresponds to the case of FIG. 7, and the maximum valve operating angle can be achieved in the intake stroke. As a result, the intake air amount can be adjusted without using the throttle valve 26. FIG. 8 shows a case where the valve timing is changed by the valve timing adjusting mechanism 58 at the same time.

  A shaft slide mechanism 100 that moves the control shaft 82 in the axial direction is shown in FIG. The shaft slide mechanism 100 includes a drive motor 102 (corresponding to an actuator), a spiral cam 104 (corresponding to a control shaft position adjusting mechanism), and a slide sensor 50 (corresponding to a sensor for detecting valve characteristics by the control shaft).

  The drive motor 102 is fixed to the cylinder head 10, and power supply from a battery corresponding to a drive force supply source is controlled by a drive signal from the ECU 4. As a result, the driving motor 102 can change the rotational phase of the spiral cam 104 by rotating the cam shaft 104a. The drive motor 102 may directly rotate the spiral cam 104, but may also rotate at a reduced speed via a gear. The rotation of the spiral cam 104 is limited to a range Kθ smaller than 360 °. If the rotation exceeds this range Kθ, the rotation of the camshaft 104a is mechanically blocked by the stopper.

  The detection rod 50a of the slide sensor 50 is fixed to a cam frame 110 provided at one end of the control shaft 82 as shown in FIG. The ECU 4 detects the valve operating angle of the intake valve 2a by measuring the amount of movement of the cam frame 110 linked to the control shaft 82 from the detection coil 50b of the slide sensor 50 fixed to the cylinder head 10 side.

  The relationship between the rotation angle θv of the cam shaft 104a and the valve operating angle VL as shown in FIG. 10 is realized by the function of the spiral cam 104 described above. FIG. 12 shows the relationship and operation between the spiral cam 104 and the control shaft 82 which set the relationship shown in FIG.

  A cam frame 110 provided at one end of the control shaft 82 houses a spiral cam 104 in an internal space. The cam frame 110 is in contact with the spiral cam surface 108 of the spiral cam 104 on the inner peripheral surface 110 a opposite to the side on which the control shaft 82 is attached. The inner peripheral surface 110a is a plane formed perpendicular to the axial direction of the control shaft 82, but may be formed in a protruding shape toward the spiral cam surface 108 instead of the plane. A spring force is applied to the cam frame 110 or the control shaft 82 in the direction shown in the drawing so that the inner peripheral surface 110a is always in contact with the spiral cam surface 108. If the axial force applied from the intake valve 2a to the control shaft 82 via the intermediate drive mechanism 60 is a certain level, it is not necessary to apply the spring force.

  Here, the position of the cam frame 110 is adjusted as follows. As shown in FIG. 12A, when the drive motor 102 (FIG. 9) is rotated until the spiral cam 104 reaches the limit position on the minimum valve operating angle side, the spiral cam 104 is the most cam in the spiral cam surface 108. The side close to the shaft 104 a, that is, the lowest cam surface portion is in contact with the inner peripheral surface 110 a of the cam frame 110. At this time, the cam frame 110 moves in the L direction as much as possible, and in conjunction with the cam frame 110, the control shaft 82 also moves in the L direction as much as possible by a spring force or an axial force. Therefore, the minimum valve operating angle state shown in FIG. 6 is realized.

  When the drive motor 102 is rotated and the spiral cam 104 is rotated in the direction of the arrow as shown in FIG. 12B, the height of the spiral cam surface 108 is gradually increased, whereby the inner circumference of the cam frame 110 is increased. The surface 110a is pushed to the right in the figure, and the entire cam frame 110 also moves in the H direction. In conjunction with this, the control shaft 82 also moves in the H direction against the spring force or axial force. Therefore, the valve working angle increases.

  Then, as shown in FIG. 12C, when it further rotates in the direction of the arrow, the highest place in the spiral cam surface 108 comes into contact with the inner peripheral surface 110a of the cam frame 110. At this time, the cam frame 110 is moved in the H direction as much as possible, and the control shaft 82 is also moved in the H direction as much as possible against the spring force or the axial force in conjunction with the cam frame 110. Therefore, the maximum valve operating angle state shown in FIG. 7 is realized.

  As shown in FIGS. 9 and 10, the spiral cam surface 108 does not change the height of the cam surface even when the rotation angle θv of the spiral cam 104 changes within the range of the width dθx on the maximum valve operating angle side. A working angle region 108a exists. The cam surface portion of the invariable working angle region 108a forms an arc surface having the rotation center P of the cam shaft 104a as an axis. Therefore, in the invariable operating angle region 108a, the control shaft 82 does not move regardless of the rotational phase of the spiral cam 104, and the valve operating angle of the intake valve 2a is maintained at the maximum valve operating angle.

  That is, the spiral cam 104 can rotate from the state shown in FIG. 12C to the state shown in FIG. 12D. In the state shown in FIG. 12D, the spiral cam 104 can be rotated further by a stopper provided inside the shaft slide mechanism 100. Is prevented from rotating. The cam surface portion with which the inner peripheral surface 110a of the cam frame 110 abuts in the state of FIG. 12C is the starting position of the invariable working angle region 108a. In the state of FIG. 12D, the inner peripheral surface 110a of the cam frame 110 is still in contact with the invariable working angle region 108a. Therefore, in the rotation of FIG. 12C to FIG. The intake valve 2a is maintained at the maximum valve operating angle.

  The spiral cam surface 108 of the spiral cam 104 receives spring force and axial force from the inner peripheral surface 110 a of the cam frame 110. When this force is received by the spiral cam surface 108 other than the invariable working angle region 108a, a rotational force in the direction opposite to the illustrated arrow is received. Therefore, in order to maintain the phase of the spiral cam 104, it is necessary to continuously output a torque that opposes the rotational force to the driving motor 102. As shown in FIG. 11, the output torque for holding increases as the rotation angle θv increases and the valve operating angle increases. However, when receiving in the invariable working angle region 108a, no rotational force is generated. Accordingly, the output of the driving motor 102 for maintaining the phase of the spiral cam 104 is zero in the invariable working angle region 108a.

  The ECU 4 controls the drive motor 102 when the engine 2 is stopped, and executes an initial state setting process in which the position where the inner peripheral surface 110a of the cam frame 110 abuts is set to the invariable working angle region 108a. For example, when the engine stop request is made, the fuel injection from the fuel injection valve 16 is stopped and the engine operation is stopped, and then the slide sensor 50 is moved to the state shown in FIG. Then, the drive motor 102 is further rotated slowly to bring the drive motor 102 into a state shown in FIG. The arrival at (D) in FIG. 12 is determined by an increase in the amount of current when stopping at the stopper. When the state transfer to (D) in FIG. 12 is completed in this way, an initial flag indicating the initial state is set to “ON” in the nonvolatile memory.

  Therefore, normally, when the engine is started, the valve operating angle of the intake valve 2a is the maximum valve operating angle. As a result, the engine 2 is started in the initial state (= maximum valve operating angle).

  The valve timing adjustment mechanism 58 shown in FIG. 1 is composed of an oil control valve (hereinafter referred to as “OCV”) and a hydraulic rotation mechanism. The valve timing is changed by shifting the rotational phase between the intake camshaft 64 and the crankshaft 6a by controlling the hydraulic pressure distribution from the OCV to each hydraulic chamber of the hydraulic rotation mechanism by duty control by the ECU 4. The valve operating angle and valve timing are controlled as shown in FIG. 8 by functioning together with the valve operating angle adjusting mechanism 56 described above.

Next, the valve working angle control process based on the detected value of the slide sensor 50 by the ECU 4 will be described.
FIG. 13 shows a flowchart of the valve working angle control process. This process is a process that is repeatedly executed at a constant time period.

  When this process is started, it is first determined whether or not the valve operating angle is in the initial state described above (S102). Here, as described above, it is determined whether or not the initial flag indicating the initial state recorded in the nonvolatile memory is “ON”. Considering that this is the case of engine start, if the initial flag = “ON” (“YES” in S102), an abnormality of the slide sensor 50 is diagnosed (S104). The slide sensor 50 is measured by two coils provided inside for self-abnormal diagnosis, and the ECU 4 has an abnormality when a difference between output values from the two coils becomes large. Diagnosis processing can be performed. In the present embodiment, the abnormality of the slide sensor 50 is always diagnosed when the valve operating angle is in the initial state.

  Next, it is determined whether or not the slide sensor 50 has been diagnosed as abnormal in the abnormality diagnosis processing in step S104 (S106). If it is not abnormal (“NO” in S106), the valve operating angle variable control process during normal operation is executed (S110). That is, a load factor (a ratio of the load to the maximum engine load) is calculated from a map determined in advance based on the operating state of the engine 2, in this case, the accelerator opening ACCP and the engine speed NE, and based on this load factor. To set the target valve operating angle. And the process which controls the drive motor 102 based on the detected value of the slide sensor 50 so that it may become this target valve working angle is performed.

  In the case of the cold start, the valve working angle control process in step S110 is preferentially performed to maintain the valve working angle in the initial state until the warm-up is completed. For this reason, even if it is determined that there is no abnormality in the slide sensor 50 until the warm-up is completed, “YES” is determined in step S102, and the abnormality diagnosis (S104) of the slide sensor 50 is continued.

  For example, if an abnormality has already occurred in the slide sensor 50 while the engine 2 is stopped (“YES” in S106), then a valve working angle holding process at the time of abnormality is executed (S108). This valve working angle holding process is a process for maintaining the current state in which the valve working angle is in the initial state. That is, as described in step S110, the valve operating angle variable control process during normal operation is not executed and the valve operating angle is maintained so as not to be changed from the initial state.

  In the initial state, it is the invariable working angle region 108 a that is in contact with the cam frame 110, so that no rotational torque is generated in the spiral cam 104. For this reason, as the valve working angle holding process, the energization to the driving motor 102 may be simply stopped so that no driving force is generated. However, the contact position of the cam frame 110 may deviate from the invariable working angle region 108a due to engine vibration generated during engine operation during retreat travel. Therefore, in the present embodiment, in consideration of this vibration, torque in the direction in which the valve operating angle increases with respect to the spiral cam 104 is applied by the drive motor 102 in a state where the output is lower than in normal driving. ing. Even if the spiral cam 104 tries to rotate by continuing such drive control on the drive motor 102, it is held by the stopper provided in the shaft slide mechanism 100 in the state shown in FIG.

  Thus, if it is determined that the slide sensor 50 is in a failure state in the variable valve mechanism 54, this abnormality is notified to the driver by a warning lamp on the dashboard. However, since the valve operating angle of the intake valve 2a is in the initial state, the engine 2 can be started, and retreat travel is possible by controlling the throttle valve 26 and controlling the fuel injection amount from the fuel injection valve 16, so that the driver Can drive the vehicle to the repair shop.

  As a result of the continuation of the valve working angle holding process (S108), “YES” is determined in step S102 even after the start, and the abnormality diagnosis (S104) of the slide sensor 50 is repeated. If the diagnosis of abnormality is repeated (“YES” in S106), the valve working angle holding process (S108) is continued.

  Further, when the slide sensor 50 returns to a normal state, “NO” is determined in step S106, so that the valve operating angle variable control process (S110) during normal operation is executed. become. As a result, when the valve operating angle leaves the initial state, “NO” is determined in step S102, and thereafter, the valve operating angle variable control process (S110) during normal operation is continued.

  Further, the ECU 4 prevents the valve operating angle from becoming abnormal when the valve timing adjusting mechanism 58 fails even when the engine is operating. = It may be the initial position. At this time, the initial flag is set to “ON”.

  Even in such a case, an abnormality diagnosis of the slide sensor 50 is executed by determining “YES” in step S102. Accordingly, if the slide sensor 50 further becomes abnormal after the failure of the valve timing adjusting mechanism 58, the valve working angle holding process (S108) will continue as long as the abnormality of the slide sensor 50 continues even if the valve timing adjusting mechanism 58 recovers thereafter. ) Is also continued and the valve operating angle is maintained in the initial state.

  An example of control in the present embodiment is shown in the timing chart of FIG. In the example of FIG. 14A, after the engine is stopped (t0), the spiral cam 104 is rotated by the drive motor 102 so that the valve operating angle is in the initial state (t1). Thereafter, when the ignition is turned on to start the engine (t2), an abnormality diagnosis of the slide sensor 50 is executed with the valve operating angle maintained in the initial state (t2 to t3). During this period (t2 to t3), engine start by cranking is also started. Since it is determined that there is no abnormality (t3), the routine shifts to the variable valve operating angle control process during normal operation (t3 to t4), and the variable valve operating angle control process during normal operation is executed (t4 to).

  FIG. 14B shows an example at the time of cold start. During the time t10 to t13, the transition is made in the same way as the time t0 to t3 in the case of (A), and it is determined that the slide sensor 50 is not abnormal, but the valve operating angle is kept in the initial state during warm-up. (T13 to t14). When the warm-up is completed (t14), the process shifts to the valve operating angle variable control process during normal operation (t14 to t15), and thereafter the valve operating angle variable control process during normal operation is executed (t15 to).

  FIG. 14C shows an example in which the slide sensor 50 is diagnosed as abnormal in the abnormality diagnosis. The transition between time t20 and t23 is similar to the time t0 to t3 in the case of (A), and it is determined that the slide sensor 50 is abnormal in the abnormality diagnosis (t22 to t23). Therefore, after that (t23-), the valve working angle continues to maintain the initial state. This makes it possible to start and retreat.

  In the configuration described above, the relationship with the claims corresponds to steps S102 and S104 of the valve working angle control processing (FIG. 13) as processing as failure diagnosis means, and steps S106 and S108 as processing as valve state holding means. . The initial state process in which the initial state of the valve operating angle is realized at the start by the ECU 4 being executed when the engine 2 is stopped corresponds to the process as the start valve characteristic setting means.

According to the first embodiment described above, the following effects can be obtained.
(I). The abnormality diagnosis (S104) of the slide sensor 50 is executed when the valve operating angle is in the initial state. The initial state is set to a valve characteristic state in which the valve operating angle is maximum. This maximum valve operating angle corresponds to the retreat travelable region, and is a valve operation angle at which the engine 2 can be started and retreat travel operation can be performed.

  Therefore, even if it is difficult to adjust the valve operating angle by rotating the spiral cam 104 due to the failure of the slide sensor 50, the retreat travel can be performed only by maintaining the current initial state by the retention control (S108). Can do.

In this way, it is possible to increase the certainty of the retreat travel when a failure occurs in the variable valve mechanism 54.
(B). In this embodiment, the spiral cam 104 configured as described above is used. For this reason, even if the cam frame 110 is kept in contact with the invariable operating angle region 108a, torque due to pressure from the cam frame 110 is not generated in the spiral cam 104. Therefore, the power supply to the drive motor 102 can be stopped during the valve working angle holding process. When the control is performed in this way, it is possible to maintain the valve characteristics that can surely perform the retreat travel without consuming the drive energy after the determination of the failure.

  In the example described in the present embodiment, the drive motor 102 is rotated in the direction in which the valve working angle increases in order to prevent the valve working angle from deviating from the initial state due to vibration during engine operation. . Even in this case, the driving force output of the driving motor 102 may be a lower level output than the normal output, so that the energy for driving can be reduced.

  Furthermore, this low level output prevents the valve operating angle adjustment mechanism 56 from moving the control shaft 82 at high speed. Therefore, even if the control shaft 82 moves to the end, the internal member of the variable valve mechanism 54 and the control shaft 82 are prevented from colliding with the stopper or the like at high speed, so that the durability of the variable valve mechanism 54 is improved. It is possible to prevent the driver from feeling uncomfortable due to the impact sound.

  (C). In particular, since the valve operating angle is set to the initial state at the time of stop by the initial state processing, the valve operating angle is equal to the initial state at least at the time of starting. Therefore, the abnormality of the slide sensor 50 can be immediately diagnosed at the time of starting, and if it is a failure, it can be started immediately only by holding control and can be shifted to retreat traveling.

In this way, it is possible to further increase the certainty of retreat travel when a failure occurs in the variable valve mechanism 54.
[Embodiment 2]
In the present embodiment, the valve working angle holding process is executed in the case of a failure of the drive motor 102 that is an actuator. For this purpose, a valve working angle control process shown in FIG. 15 and a drive motor failure diagnosis process shown in FIG. 16 are executed instead of the valve working angle control process (FIG. 13). Other configurations are the same as those of the first embodiment, and will be described with reference to FIGS.

The valve working angle control process (FIG. 15) will be described. This process is a process that is repeatedly executed at a constant time period.
When this process is started, it is first determined whether or not the valve operating angle is in an initial state (S202). This determination is as described in step S102 of the valve operating angle control process (FIG. 13). That is, if the initial flag = “ON” (“YES” in S202), it is determined whether or not a failure diagnosis of the drive motor 102 has not yet been performed at the time of the current start (S204).

  If failure diagnosis of the drive motor 102 has not been performed (“YES” in S204), execution of failure diagnosis processing for the drive motor 102 is set (S206). This drive motor failure diagnosis processing is as shown in the flowchart of FIG. 16, and is repeatedly executed at a time period.

  The drive motor failure diagnosis process (FIG. 16) will be described. First, it is determined whether or not the failure diagnosis result on the valve operating angle increase side is normal (S252). If it is at the time of starting the failure diagnosis, no diagnosis result has been obtained yet (“NO” in S252), and then the valve working angle increasing side failure diagnosis is performed (S254). In this valve working angle increasing side failure diagnosis, first, in order to finely drive the driving motor 102, a process of rotating the spiral cam 104 toward a larger valve working angle is performed by supplying less electric power than during normal control. This fine driving process is performed by a stopper in the valve operating angle adjusting mechanism 56 when the driving motor 102 is actually driven normally and the contact position of the cam frame 110 moves on the invariable operating angle area 108a. If the movement is blocked, it will take place within the scheduled time. During this fine drive process, the ECU 4 measures the amount of current flowing to the drive motor 102.

  If the driving motor 102 is normally driven, the stopper prevents the movement, and if the driving motor 102 is forcibly stopped, the amount of current to the driving motor 102 increases. Therefore, the ECU 4 detects whether or not this current amount increase has occurred within the above-mentioned scheduled time, and if the corresponding current amount increase occurs, it is assumed that the drive motor 102 has not failed on the valve operating angle increase side. If not, diagnose that it is broken.

  After the valve working angle increasing side failure diagnosis process is started in step S254, it is determined whether or not the valve working angle increasing side failure diagnosis is completed (S256). If the failure diagnosis on the valve operating angle increasing side has not been completed (“NO” in S256), the process is temporarily terminated.

  After the next control cycle, in the valve working angle control process (FIG. 15), “YES” is determined in steps S202 and S204 until the diagnosis in the drive motor failure diagnosis process is completed, so the process in step S206 is repeated. . In the drive motor failure diagnosis process (FIG. 16), “NO” is determined in steps S252 and S256, and therefore the process in step S254 is repeated.

  In the drive motor failure diagnosis process (FIG. 16), when a failure diagnosis result on the valve working angle increase side of the drive motor 102 is obtained (“YES” in S256), the diagnosis result is normal on the valve working angle increase side. It is determined whether or not (S258).

  If the result is a normal diagnosis (“YES” in S258), the process is temporarily terminated as it is, and “YES” is determined in step S252 in the next control cycle. Then, failure diagnosis on the valve operating angle decreasing side is performed (S260). In this failure diagnosis on the valve operating angle decreasing side, first, the drive motor 102 is finely driven, and the spiral cam 104 is rotated so that the valve operating angle becomes smaller by supplying less electric power than during normal control. In this case, the fine driving process is such that the driving motor 102 is actually driven normally, and the contact position of the cam frame 110 reaches the cam surface portion that is actually spirally inclined from the invariable working angle region 108a. When it appears in the detection value of the slide sensor 50, it is performed within a scheduled time.

  Thus, if the drive motor 102 is driven normally, the detection value of the slide sensor 50 detects a decrease in the valve operating angle. Therefore, the ECU 4 detects whether or not the change in the detected value has occurred within the scheduled time. If the change has occurred, the drive motor 102 has not failed on the valve operating angle decreasing side, and if not, it has failed. It is determined that

  After starting the valve working angle decreasing side failure diagnosis process in step S260, it is determined whether or not the valve working angle decreasing side failure diagnosis is completed (S262). If the failure diagnosis on the valve operating angle decreasing side has not been completed (“NO” in S262), the process is temporarily terminated.

  After the next control cycle, in the valve working angle control process (FIG. 15), “YES” is determined in steps S202 and S204 until the diagnosis in the drive motor failure diagnosis process is completed, so the process in step S206 is repeated. . In the drive motor failure diagnosis process (FIG. 16), “YES” is determined in step S252 and “NO” is determined in step S262, and therefore the process of step S260 is repeated.

  Then, in the drive motor failure diagnosis process (FIG. 16), when a failure diagnosis result on the valve operating angle reduction side of the drive motor 102 is output (“YES” in S262), based on the detection value of the slide sensor 50, Initial state return processing (S263) is executed.

  This initial state return process is a process for reliably returning the valve operating angle to the initial state. When the drive motor 102 is driven normally in the valve operating angle decreasing side failure diagnosis process performed immediately before, the cam frame 110 is applied to the part of the spiral cam surface 108 that is actually spiraled. You are in contact. For this reason, if it is left as it is, the valve operating angle gradually decreases during start-up or during engine operation when the valve timing adjusting mechanism 58 fails, and it may become difficult to start and retreat. In order to prevent such a situation, the driving motor 102 is driven in a direction in which the valve operating angle is increased to perform a process of returning the valve operating angle to the initial state. In the case where a failure has occurred on the valve operating angle decreasing side, the cam frame 110 has not deviated from the invariable operating angle region 108a, so the initial state return process (S263) may not be executed. However, even if no decrease in the valve operating angle is detected by the slide sensor 50, there is a case where the valve operating angle is about to deviate from the invariable operating angle region 108a. May be executed.

  It should be noted that if the engine 2 has not been started during the failure diagnosis process and has not been diagnosed as having a failure, the process proceeds to the normal valve operating angle control process. The state return process (S263) may not be executed.

  After step S263, failure diagnosis completion setting is made (S264), and this process is temporarily terminated. Even when a diagnosis of an abnormality on the valve operating angle increase side is made in step S258 ("NO" in S258), failure diagnosis completion setting (S264) is made.

  When the diagnosis result of the drive motor 102 is obtained in this way, it is determined that the failure detection process has been performed in the valve operating angle control process (FIG. 15) (“NO” in S204), and then the diagnosis result is driven. It is determined whether or not the motor 102 has failed (S208).

  Here, if it is diagnosed that the drive motor 102 is in failure, that is, a failure at the time of increase or a decrease in the valve working angle (“YES” in S208), the valve working angle holding process at the time of abnormality is next performed. Is executed (S210). This valve working angle holding process is as described in step S108 of the valve working angle control process (FIG. 13). Since the valve operating angle is already in the initial state, the fine drive may be executed as described above, or the power supply to the drive motor 102 may be stopped.

  In the case of a failure, in the subsequent control cycle, “YES” is determined in step S202, “NO” is determined in step S204, and “YES” is determined in step S208, and the process in step S210 is continued.

  If it is diagnosed that the drive motor 102 is not in failure ("NO" in S208), the valve operating angle variable control process during normal operation is executed (S212). The variable valve operating angle control process during normal operation is as described in step S110 of the valve operating angle control process (FIG. 13).

  If there is no failure, “YES” in step S202, “NO” in step S204, and “NO” in step S202 in the transition period in which the valve operating angle is in the initial state in the control cycle of the subsequent valve operating angle control process (FIG. 15). It is determined as “NO” in S208, and the process of step S212 is performed. When the valve operating angle leaves the initial state, “NO” is determined in step S202 and “NO” in step S208, and the process in step S212 is continued.

  Further, when the valve timing adjusting mechanism 58 fails as described above, the ECU 4 may set the initial flag = “ON” with the valve operating angle = initial position. Even in such a case, by determining “YES” in step S202, processing similar to that at the time of engine start described above is performed.

  An example of the control in this embodiment is shown in the timing chart of FIG. (A) is when the drive motor 102 is not broken down, (B) is when the drive motor 102 is not broken at the cold start, and (C) is broken down by the failure diagnosis. This is an example when it is determined that the In each case, there is a failure diagnosis period (t32 to t33, t42 to t43, t52 to t53) of the driving motor 102 instead of the abnormality diagnosis of the slide sensor 50, and the flow of processing is shown only in this period becoming longer. 14 as described above.

  In the configuration described above, the relationship with the claims is that the steps S202 and S206 of the valve working angle control process (FIG. 15) and the drive motor failure diagnosis process (FIG. 16) are the processes as the failure diagnosis means. Corresponds to processing as a valve state holding means.

According to the second embodiment described above, the following effects can be obtained.
(I). Even when the drive motor 102 fails, the effects as described in the first embodiment (A) to (C) are produced.

  (B). The drive of the drive motor 102 performed for failure diagnosis is also performed in a low level output state as compared with the drive force output in the normal state. For this reason, even if it collides with the stopper, the momentum at the time of the collision can be reduced, so that the durability of the valve operating angle adjustment mechanism 56 can be improved and the uncomfortable feeling to the driver due to the impact sound can be prevented.

  (C). As a failure diagnosis, the drive motor 102 is driven first in the direction in which the valve operating angle is increased. As a result, if the valve operating angle becomes larger and a failure occurs, the valve operating angle is maintained in the initial state by immediately holding control, so that starting and retreating are possible.

  Then, when it is determined that there is no failure when the valve operating angle is increased, the drive motor 102 is driven to the direction where the valve operating angle is decreased for the first time when the valve operating angle is decreased. Is judged. Even if a failure is found by this determination, the valve can be driven in the direction where the valve operating angle becomes larger, so that the valve operating angle can be immediately increased to obtain an initial state or a valve operating angle higher than this.

As a result, the certainty of the retreat travel when a failure occurs in the variable valve mechanism 54 can be improved.
[Embodiment 3]
In the present embodiment, instead of the shaft slide mechanism 100 of the second embodiment, a shaft slide mechanism 300 having a worm gear is used as shown in FIG. 18, and a failure of the slide sensor 314 is detected and dealt with. Different. Although the processing is executed in the same flow as the valve working angle control processing (FIG. 13), the processing contents differ as described later by using the shaft slide mechanism 300 provided with the worm gear. Other configurations are the same as those of the first embodiment, and will be described with reference to FIGS.

  The shaft slide mechanism 300 will be described. The shaft slide mechanism 300 includes a worm gear 304 that is rotated by a driving motor 302 and a driven gear 306 that is rotated by the worm gear 304. The driven gear 306 is formed integrally with the female screw portion 310 of the speed reducer 308. A male screw portion 312 of the speed reducer 308 screwed with the female screw portion 310 is fixed to one end of the control shaft 82. As a result, when the driving motor 302 rotates, the female screw portion 310 rotates via the worm gear 304 and the driven gear 306, and as a result, the male screw portion 312 of the speed reducer 308 moves in the axial direction together with the control shaft 82. . As a result, the valve working angle of the intake valve 2a can be adjusted.

  The axial position of the control shaft 82 is detected by the slide sensor 314. The slide sensor 314 includes a detection rod 314a fixed to the male screw portion 312 of the speed reducer 308 and a detection coil 314b fixed to the cylinder head 10 side. The ECU 4 can measure the slide amount of the control shaft 82 based on the signal from the detection coil 314b into which the tip of the detection rod 314a is inserted, and can detect the valve operating angle of the intake valve 2a.

  The relationship between the rotation angle θw of the worm gear 304 and the valve operating angle VL when this shaft slide mechanism 300 is used is as shown in FIG. In FIG. 19, the valve operating angle changes monotonously according to the change of the rotation angle θw, and there is no invariable operating angle region as described in FIG. 10 of the first embodiment.

  The relationship between the output torque of the drive motor 302 and the moving speed of the control shaft 82 is shown in FIG. Since the shaft slide mechanism 300 uses the worm gear 304, even if torque is output from the drive motor 302, there is a non-operation region where the control shaft 82 cannot move due to friction before and after the output torque = 0. Therefore, the valve operating angle can be maintained by setting the output torque of the driving motor 302 to “0” even if there is no invariable operating angle region. Moreover, it can be maintained at an arbitrary valve working angle.

  Using such a function of the shaft slide mechanism 300, the ECU 4 executes a valve working angle control process. Although the content of the process is different, the flow is the same as in FIG. 13 and will be described with reference to FIG.

  When this process is started, it is first determined whether or not the valve operating angle is in the initial state described above (S102). Here, when it is time to start the engine, it is determined whether or not the initial flag indicating the initial state recorded in the nonvolatile memory is “ON”.

In the present embodiment, as shown in FIG. 19, the initial state VLini is set not at the maximum valve operating angle VLmax but at a slightly smaller position.
Therefore, the ECU 4 controls the drive motor 302 based on the measured value of the slide sensor 314 when the engine 2 is stopped as the initial state processing, and executes processing for setting the valve operating angle to the initial state VLini. When the movement to the initial state VLini is completed, an initial flag indicating the initial state is set to “ON” in the nonvolatile memory.

  Therefore, at least when the engine is started, the valve operating angle of the intake valve 2a is in the initial state VLini. This initial state VLini is adapted from the exhaust gas recirculation rate by the valve overlap and the intake efficiency, and differs depending on the type of engine.

  If the initial flag = “ON” (“YES” in S102), an abnormality of the slide sensor 314 is diagnosed (S104). As described in the first embodiment, the slide sensor 314 is provided with two coils for self-abnormality diagnosis. Therefore, the ECU 4 can perform failure diagnosis by comparing the outputs of the coils.

  Next, it is determined whether or not the slide sensor 314 is diagnosed as abnormal in the abnormality diagnosis process (S106). If it is not abnormal (“NO” in S106), the valve operating angle variable control process during normal operation is executed (S110). That is, a load factor is calculated from a map determined in advance by experiments based on the operating state of the engine 2, and a target valve operating angle is set based on this load factor. And the process which controls the drive motor 302 based on the detected value of the slide sensor 314 so that it may become this target valve working angle is performed.

In the case of the cold start, the process of maintaining the valve operating angle in the initial state is preferentially performed until the warm-up is completed as described in the first embodiment.
If an abnormality has occurred in the slide sensor 314 while the engine 2 is stopped (“YES” in S106), then a valve working angle holding process at the time of abnormality is executed (S108). This valve working angle holding process is a process of maintaining the current state in which the valve working angle is in the initial state VLini. That is, this is a process of holding the valve operating angle in the initial state VLini without executing the variable valve operating angle control process during normal operation as described in step S110.

  Since the shaft slide mechanism 300 uses the worm gear 304, the initial state VLini can be maintained even if the power supply to the drive motor 302 is stopped as described in FIG. Therefore, as the valve working angle holding process, it is possible to simply stop energization of the driving motor 302 so as not to generate a driving force.

  However, even in this case, the relative torque between the worm gear 304 and the driven gear 306 exceeds the non-operating region even if the drive motor 302 is not energized due to vibration caused by engine operation during retreat travel. May end up. In particular, if the non-operating region is exceeded on the side of reducing the valve operating angle due to vibration, the driven gear 306 may rotate and the valve operating angle may be smaller than the initial state VLini. In consideration of this, power may be supplied to the drive motor 302 to output torque in a direction in which the valve operating angle increases. That is, for example, the output torque in the range indicated by F in FIG. This makes it possible to hold the valve operating angle in the initial state VLini more reliably even when vibrations are generated.

  When the valve operating angle is held in the initial state VLini as described above, the valve operating angle of the intake valve 2a is in a state where starting and retreating are possible. Therefore, the engine 2 is started and the throttle valve 26 is controlled. By controlling the fuel injection amount from the fuel injection valve 16, the driver can retreat the vehicle to the repair shop.

  Then, by executing the valve working angle holding process (S108), the valve working angle is equal to the initial state VLini ("YES" in S102) and the slide sensor 314 abnormality diagnosis (S104) is repeated even after starting. If it is abnormal again (“YES” in S106), the valve working angle holding process (S108) is continued. Further, when the slide sensor 314 returns to a normal state, “NO” is determined in step S106, so that the valve operating angle variable control process (S110) during normal operation is executed. become. As a result, when the valve operating angle leaves the initial state, “NO” is determined in step S102, and thereafter, the valve operating angle variable control process (S110) during normal operation is continued.

  Further, when the valve timing adjusting mechanism 58 fails even during engine operation, the ECU 4 sets the valve operating angle = initial position and the initial flag = “ON” for the reason described in the first embodiment. There is.

  Even in such a case, an abnormality diagnosis of the slide sensor 314 is performed by determining “YES” in step S102 (S104). Therefore, if the slide sensor 314 becomes abnormal after the failure of the valve timing adjusting mechanism 58, the valve operating angle holding process (S108) continues as long as the abnormality of the slide sensor 314 continues even if the valve timing adjusting mechanism 58 recovers thereafter. ) Will continue.

In the above-described configuration, the relationship with the claims is as described in the first embodiment.
According to the third embodiment described above, the following effects can be obtained.
(I). Although the worm gear 304 is used as the shaft slide mechanism 300 and the retractable travelable region is not the maximum valve operating angle, the effects (a) to (c) of the first embodiment are produced.

  In order to prevent vibration during engine operation, torque is generated from the drive motor 302 in a direction in which the valve operating angle increases. Even in this case, the drive force output of the drive motor 302 is an output in a normal state. Therefore, a lower level of output is sufficient, and less energy is required for generating torque. Furthermore, since this low level output does not move the control shaft 82, the internal member of the variable valve mechanism 54 and the control shaft 82 are prevented from colliding with a stopper or the like at high speed. For this reason, the durability of the variable valve mechanism 54 can be improved, and a sense of incongruity to the driver due to an impact sound can be prevented.

(B). Since the initial state can be obtained at any position of the valve operating angle by the relationship shown in FIG. 20, the degree of application is increased regardless of the type of engine.
[Embodiment 4]
In the present embodiment, the valve working angle holding process is executed when the drive motor 302 shown in FIG. 18 fails. For this purpose, the processing shown in FIGS. 15 and 16 of the second embodiment is performed instead of the valve working angle control processing (FIG. 13). However, although the processing flow is as shown in FIGS. 15 and 16, the content of the processing is different because the shaft slide mechanism 300 shown in FIG. 18 is used. The other configuration is the same as that of the third embodiment, and will be described with reference to FIGS.

The valve working angle control process (FIG. 15) will be described. This process is a process that is repeatedly executed at a constant time period.
When this process is started, it is first determined whether or not the valve operating angle is in the initial state described above (S202). This determination is the same as step S102 described in the third embodiment. That is, if the initial flag = “ON” (“YES” in S202), it is determined whether or not the failure diagnosis of the drive motor 302 has not yet been performed since the current valve operating angle = initial state VLini. It is determined (S204).

  If failure diagnosis of the drive motor 302 has not been performed (“YES” in S204), execution of failure diagnosis processing for the drive motor 302 is set (S206). This drive motor failure diagnosis process is performed according to the flow shown in FIG. Next, drive motor failure diagnosis processing (FIG. 16) will be described.

  First, it is determined whether or not the failure diagnosis result on the valve operating angle increase side is normal (S252). If it is at the time of starting the failure diagnosis, no diagnosis result has been obtained yet (“NO” in S252), and then the valve working angle increasing side failure diagnosis is performed (S254). In this valve working angle increasing side failure diagnosis, first, a process of gradually increasing the output torque to the driving motor 302 is performed in order to increase the valve working angle. When the drive motor 302 is normal, the valve operating angle increases if the output torque exceeds the non-operating region on the plus side as shown in FIG. Therefore, a process of gradually increasing the output torque is performed until it is confirmed by the slide sensor 314 that the valve operating angle has increased. However, if the drive motor 302 is normal, the output torque is returned to 0 unless the slide sensor 314 confirms that the valve operating angle has increased even after the estimated time for the output of the slide sensor 314 to change.

  Therefore, the ECU 4 detects whether or not an increase in the valve operating angle detected by the slide sensor 314 has occurred within the scheduled time. If the valve operating angle increases, it is determined that the drive motor 302 has not failed. If not, it is determined that there is a failure.

  After the valve working angle increasing side failure diagnosis process is started in step S254, it is determined whether or not the valve working angle increasing side failure diagnosis is completed (S256). Here, if the valve working angle increasing side failure diagnosis is not completed (“NO” in S256), this processing is once ended.

  After the next control cycle, in the valve working angle control process (FIG. 15), “YES” is determined in steps S202 and S204 until the diagnosis in the drive motor failure diagnosis process is completed, so the process in step S206 is repeated. . In the drive motor failure diagnosis process (FIG. 16), “NO” is determined in steps S252 and S256, and therefore the process in step S254 is repeated.

  In the drive motor failure diagnosis process (FIG. 16), if a failure diagnosis result on the valve working angle increasing side of the driving motor 302 is obtained (“YES” in S256), the diagnosis result is normal on the valve working angle increasing side. It is determined whether or not (S258).

  If the result is a normal diagnosis (“YES” in S258), the process is temporarily terminated as it is, and “YES” is determined in step S252 in the next control cycle. Then, failure diagnosis on the valve operating angle decreasing side is performed (S260). In the valve working angle decreasing side failure diagnosis, first, a process of gradually increasing the output torque to the driving motor 302 is performed in such a manner that the valve working angle becomes smaller. When the drive motor 302 is normal, the valve operating angle decreases if the output torque exceeds the non-operating region to the minus side as shown in FIG. Therefore, a process of gradually increasing the output torque is performed until it is confirmed by the slide sensor 314 that the valve operating angle has decreased. However, if the drive motor 302 is normal, the output torque is returned to 0 unless the slide sensor 314 confirms that the valve operating angle has decreased even after the estimated time for the output of the slide sensor 314 to change.

  After starting the valve working angle decreasing side failure diagnosis process in step S260, it is determined whether or not the valve working angle decreasing side failure diagnosis is completed (S262). Here, if the valve operating angle decreasing side failure diagnosis is not completed (“NO” in S262), the present process is temporarily ended.

  After the next control cycle, in the valve working angle control process (FIG. 15), “YES” is determined in steps S202 and S204 until the diagnosis in the drive motor failure diagnosis process is completed, so the process in step S206 is repeated. . In the drive motor failure diagnosis process (FIG. 16), “YES” is determined in step S252 and “NO” is determined in step S262, and therefore the process of step S260 is repeated.

  Then, in the drive motor failure diagnosis process (FIG. 16), if a failure diagnosis result on the valve operating angle decreasing side of the drive motor 302 is output (“YES” in S262), based on the detection value of the slide sensor 314, Initial state return processing (S263) is executed.

  This initial state return process is a process for reliably returning the valve operating angle to the initial state. When the driving motor 302 is driven normally in the valve operating angle decrease side failure diagnosis process performed immediately before, the valve operating angle change in the immediately preceding valve operating angle increase side failure diagnosis process is canceled out. The valve operating angle should have returned to the initial state VLini shown in FIG. However, the change in the valve working angle by the failure diagnosis on the valve working angle increase side and the change in the valve working angle by the failure diagnosis on the valve working angle decrease side are not necessarily the same. In particular, when the valve operating angle is in a state smaller than the initial state VLini, if the valve operating angle is left as it is, there is a possibility that the start cannot be stably performed. In order to prevent such a situation, processing for returning the valve operating angle to the initial state VLini by the driving motor 302 is performed (S263).

  In the case of failure on the valve operating angle decreasing side, the valve operating angle is larger than the initial state VLini. In this case as well, the valve operating angle is returned to the initial state VLini. However, since the valve operating angle is large, it is not necessary to return to the initial state VLini.

  Subsequent to step S263, failure diagnosis completion setting is made (S264), and the process is temporarily terminated. Even when a diagnosis of an abnormality on the valve operating angle increasing side is made in step S258 (“NO” in S258), a failure diagnosis completion setting is made (S264).

  When the diagnosis result of the drive motor 302 is obtained in this way, it is determined in the valve working angle control process (FIG. 15) that the failure detection process has been performed (“NO” in S204), and then the diagnosis result is driven. It is determined whether or not the motor 302 has failed (S208).

  If it is diagnosed that the drive motor 302 is in failure, that is, a failure at the time of increasing the valve working angle or a failure at the time of decreasing (“YES” in S208), the valve working angle holding process at the time of abnormality is next performed. Is executed (S210). This valve working angle holding process is the same as the valve working angle holding process (S108) of the valve working angle control process (FIG. 13) described in the third embodiment.

  In the case of a failure, the valve operating angle is actually the initial state VLini or larger than the initial state VLini. In this failure state, the initial flag remains “ON”. Therefore, in the subsequent control cycle, “YES” is determined in step S202, “NO” in step S204, and “YES” in step S208. The process of S210 will continue.

  If it is diagnosed that the drive motor 302 is not in failure ("NO" in S208), the valve operating angle variable control process during normal operation is executed (S212). The variable valve operating angle control process during normal operation is as described in step S110 of the valve operating angle control process (FIG. 13) described in the third embodiment.

  If there is no failure, the initial flag is set to “OFF”. Therefore, “NO” is determined in step S202 and “NO” in step S208 in the control cycle of the subsequent valve operating angle control process (FIG. 15). Thus, the process of step S212 is continued.

  Further, when the valve timing adjusting mechanism 58 fails as described above, the ECU 4 may set the initial flag = “ON” with the valve operating angle = initial position. Even in such a case, by determining “YES” in step S202, processing similar to that at the time of engine start described above is performed.

  In the configuration described above, the relationship with the claims is that the steps S202 and S206 of the valve working angle control process (FIG. 15) and the drive motor failure diagnosis process (FIG. 16) are the processes as the failure diagnosis means. Corresponds to processing as a valve state holding means.

According to the fourth embodiment described above, the following effects can be obtained.
(I). Even when the drive motor 302 fails, the effects described in the third embodiment (A) and (B) are produced.

[Other embodiments]
(A). In the above embodiment, the minimum value of the valve operating angle is “0”, but the minimum value of the valve operating angle may be a valve operating angle that opens the intake valve 2a to some extent. Even in this case, since the valve operating angle appropriate for starting is a larger value, it is possible to prevent the starting and retreating from being disabled when the sensor or the actuator fails according to the present invention.

  (B). In the above embodiment, the slide sensors 50 and 314 are used to detect the valve working angle. However, the rotation angle sensor that detects the rotational phase of the drive motors 102 and 302, the spiral cam 104, or the speed reducer 308 uses the valve. The working angle may be detected.

  (C). In the fourth embodiment, in the failure diagnosis of the drive motor 302, the valve operation angle increasing side failure diagnosis (FIG. 16: S254) is executed first, and if there is no failure on the valve operation angle increasing side, then the valve operation angle is decreased. Side failure diagnosis (FIG. 16: S260) was performed. Instead, the valve working angle decreasing side failure diagnosis may be executed first, and if there is no failure on the valve working angle decreasing side, the valve working angle increasing side failure diagnosis may be executed next. In this case, the valve operating angle is slightly increased in the initial state. Specifically, the initial state is set to a valve operating angle that is larger than the lower limit of the valve operating angle that allows retreat travel including engine start.

  As a result, if the failure is detected when the valve working angle decreasing side failure diagnosis is executed first and then the valve working angle increasing side failure diagnosis is executed, the valve working angle is smaller than the initial state, and more The valve working angle cannot be increased. However, since the valve operating angle in this state can be retracted, starting and retracting can be performed even if holding control is executed.

  (D). In the above embodiment, the mediating drive mechanism is a type in which the valve operating angle and the valve lift amount are adjusted by the axial movement of the control shaft. However, the configuration as shown in FIGS. By doing so, the valve working angle and the valve lift amount may be adjusted. That is, the intake cam 464a may be a three-dimensional cam, and the intake cam shaft 464 may also serve as a control shaft and move in the axial direction. Here, a straight spline 464b is provided at the end of the intake camshaft 464, and this straight spline 464b engages with a vane in which the phase difference with the short cylindrical casing can be adjusted inside the valve timing adjusting mechanism 58 doing. Therefore, even if the vane cannot move in the axial direction within the short cylindrical casing, the intake camshaft 464 can move in the axial direction.

  Here, the shaft slide mechanism 100 is as described in the first embodiment. However, the cam frame 110 is connected to the intake camshaft 464 via a rolling bearing portion 466. Thus, the intake camshaft 464 can be moved in the axial direction without rotating the cam frame 110 with respect to the intake camshaft 464 that is interlocked with the rotation of the crankshaft via the valve timing adjusting mechanism 58.

  In the state where the phase of the spiral cam 104 is the minimum valve operating angle as shown in FIG. 22A, the intake camshaft 464 exists at the limit position in the L direction. Therefore, the intake valve 2a is driven in contact with the low valve operating angle side of the intake cam 464a, and the valve operating angle and the valve lift amount are the smallest.

  When the spiral cam 104 is rotated by driving the motor from the state of FIG. 22A, the intake camshaft 464 moves in the H direction. As a result, the intake valve 2a comes into contact with a position away from the low valve operating angle side of the intake cam 464a, and the valve operating angle and the valve lift amount gradually increase.

  When the phase of the spiral cam 104 reaches the maximum valve operating angle as shown in FIG. 22B, the intake camshaft 464 becomes the limit position in the H direction. Therefore, the intake valve 2a is driven in contact with the high valve operating angle side of the intake cam 464a, and the valve operating angle and the valve lift amount are the largest.

  In this way, the valve operating angle and valve lift amount of the intake valve 2a can be adjusted as shown in FIG. 8, and failure diagnosis and holding control can be performed as in the first and second embodiments.

  Instead of the shaft slide mechanism 100, a shaft slide mechanism 300 using a worm gear shown in FIG. 18 may be used. As a result, failure diagnosis and holding control can be performed as in the third and fourth embodiments.

  (E). In the above embodiment, the valve operating angle and the valve lift amount are adjusted simultaneously by the valve operating angle adjusting mechanism as shown in FIG. 8, but the valve operating angle adjusting mechanism in which only the valve operating angle is adjusted. Alternatively, a valve lift amount adjusting mechanism in which only the valve lift amount is adjusted may be used.

  (F). In the above embodiment, the valve working angle and the valve lift amount are controlled for the intake valve 2a. However, the present invention can be applied to the case where the valve working angle or the valve lift amount of the exhaust valve 2b is variable.

  (G). In the above-described embodiment, the electric drive motors 102 and 302 are used. However, the control shaft 82 is moved in the axial direction by rotating the spiral cam 104 and the driven gear 306 with hydraulic pressure using a hydraulic actuator. Also good.

  (H). In the third and fourth embodiments, the initial state VLini at the time of starting the engine and the retreat travelable region set when the sensor or the actuator fails are in agreement with each other. For example, the retreat travelable region may be set closer to the maximum valve operating angle than in the initial state.

1 is a schematic configuration diagram of an engine and an ECU according to an embodiment. The longitudinal cross-sectional view of the variable valve system of the said engine. The perspective view of the mediation drive mechanism of the said variable valve system. The horizontal fracture perspective view of the above-mentioned mediation drive mechanism. The horizontal and vertical fracture perspective views of the mediating drive mechanism. Drive explanatory drawing at the time of the valve working angle and valve lift amount of the mediation drive mechanism. Drive explanatory drawing at the time of valve working angle and valve lift amount maximum of the above-mentioned mediation drive mechanism. The graph explaining the valve | bulb working angle and valve lift amount change by the said mediation drive mechanism. FIG. 3 is a configuration explanatory diagram of a shaft slide mechanism according to the first and second embodiments. The graph which shows the relationship between rotation angle (theta) v of the said spiral cam, and valve | bulb action angle VL. The graph which shows the relationship between rotation angle (theta) v of the said spiral cam, and the output torque of the drive motor required for valve | bulb working angle maintenance. Explanatory drawing of valve lift amount adjustment by the said shaft slide mechanism. 7 is a flowchart of valve working angle control processing according to the first and third embodiments. 3 is a timing chart illustrating an example of processing in Embodiment 1. 7 is a flowchart of valve working angle control processing according to the second and fourth embodiments. 7 is a flowchart of a drive motor failure diagnosis process performed in the valve working angle control process of the second and fourth embodiments. 9 is a timing chart showing an example of processing in the second embodiment. Structure explanatory drawing of the shaft slide mechanism using the worm gear used in Embodiment 3, 4. FIG. The graph which shows the relationship between rotation angle (theta) w of the driven gear rotated with the said worm gear, and valve | bulb action angle VL. The graph which shows the relationship between the motor output torque and the control shaft speed in the shaft slide mechanism using the worm gear. The perspective view which shows the example of the variable valve system of another engine. Explanatory drawing of the drive state of the variable valve system of another engine.

Explanation of symbols

  2 ... Engine, 2a ... Intake valve, 2b ... Exhaust valve, 4 ... ECU, 6 ... Piston, 6a ... Crankshaft, 8 ... Cylinder block, 10 ... Cylinder head, 12 ... Combustion chamber, 14 ... Spark plug, 16 ... Fuel Injection valve, 18 ... intake port, 20 ... intake passage, 22 ... surge tank, 24 ... throttle valve motor, 26 ... throttle valve, 28 ... throttle opening sensor, 30 ... intake air amount sensor, 32 ... intake air temperature sensor, 34 ... Exhaust port, 36 ... Exhaust passage, 38 ... Exhaust purification catalytic converter, 40 ... Air-fuel ratio sensor, 42 ... Accelerator pedal, 44 ... Accelerator opening sensor, 46 ... Engine speed sensor, 48 ... Reference crank angle sensor, DESCRIPTION OF SYMBOLS 50 ... Slide sensor, 50a ... Detection rod, 50b ... Detection coil, 52 ... Cooling water temperature sensor, 54 ... Variable valve gear 56 ... Valve working angle adjustment mechanism, 58 ... Valve timing adjustment mechanism, 60 ... Mediation drive mechanism, 62 ... Roller rocker arm, 62a ... Rocker roller, 64 ... Intake camshaft, 64a ... Intake cam, 66 ... Input section, 66a ... housing, 66b ... helical spline, 66c, 66d ... arm, 66e ... shaft, 66f ... roller, 66g ... spring, 68 ... first swing cam, 68a ... housing, 68b ... helical spline, 68c ... bearing part, 68d ... Nose, 68e ... cam surface, 70 ... second swing cam, 70a ... housing, 70b ... helical spline, 70c ... bearing, 70d ... nose, 70e ... cam surface, 72 ... slider gear, 72a ... helical spline for input, 72b ... small diameter portion, 72c ... first output helical spline, 72d ... Diameter portion, 72e ... second output helical spline, 72f ... through hole, 72g ... circumferential groove, 72h ... pin insertion hole, 80 ... support pipe, 80a ... long hole, 82 ... control shaft, 82a ... control pin, 82b ... Support hole, 100 ... shaft slide mechanism, 102 ... drive motor, 104 ... spiral cam, 104a ... cam shaft, 108 ... spiral cam surface, 108a ... invariant working angle region, 110 ... cam frame, 110a ... inner peripheral surface, DESCRIPTION OF SYMBOLS 300 ... Shaft slide mechanism, 302 ... Drive motor, 304 ... Worm gear, 306 ... Driven gear, 308 ... Reduction gear, 310 ... Female screw part, 312 ... Male screw part, 314 ... Slide sensor, 314a ... Detection rod, 314b ... Detection coil, 464 ... Suction cam shaft, 464a ... Suction cam, 464b ... Straight spline 466 ... Bearing portion.

Claims (14)

A control shaft for adjusting one or both of the valve lift amount and the valve operating angle of the internal combustion engine is driven by an actuator through a control shaft position adjusting mechanism, and the valve characteristic by the control shaft is detected by a sensor, A failure diagnosis apparatus for a variable valve mechanism in which the actuator is controlled based on a detection value of the sensor,
A failure diagnosis means for performing a failure diagnosis of the variable valve mechanism when it is determined that the valve characteristic exists in a retreatable travelable region set within the adjustment range of the valve characteristic by the variable valve mechanism;
When the failure diagnosing means diagnoses that the variable valve mechanism is out of order, the valve characteristic is maintained in a state where the variable valve mechanism is in the retreat travelable region, or greater than the retreat travel possible region. Valve state holding means for performing holding control to hold in a state;
A variable valve mechanism failure diagnosis apparatus for an internal combustion engine, comprising: 2. The variable valve mechanism failure diagnosis apparatus for an internal combustion engine according to claim 1, wherein the failure diagnosis means determines a failure of the sensor. 2. The variable valve mechanism failure diagnosis apparatus for an internal combustion engine according to claim 1, wherein the failure diagnosis means determines a failure of the actuator. The control shaft position adjusting mechanism according to any one of claims 1 to 3, wherein the control shaft position adjusting mechanism can maintain the valve characteristic without depending on the driving force of the actuator in a state where the valve characteristic exists at least in the retractable travelable region, A variable valve mechanism failure diagnosis apparatus for an internal combustion engine, wherein the valve state holding means executes the holding control by stopping driving force output from a driving force supply source to the actuator. 3. The valve state holding means according to claim 2, wherein the driving force output from the driving force supply source to the actuator is set to a direction in which the valve characteristic increases, and the output state is lower than the normal driving force output. A variable valve mechanism failure diagnosis apparatus for an internal combustion engine, wherein the holding control is executed by switching. 6. The variable valve mechanism according to claim 1, wherein the variable valve mechanism includes a spiral cam as the control shaft position adjusting mechanism, and the control shaft is moved in the axial direction by rotating the spiral cam by the actuator. The retreat travelable area is set to an adjustment state in which the valve characteristic is maximized, and the spiral cam is arranged on the cam surface corresponding to the retreat travel possible area. A variable valve mechanism failure diagnosis apparatus for an internal combustion engine, characterized by having an arcuate surface about the axis. 6. The variable valve mechanism according to claim 1, wherein the variable valve mechanism includes a worm gear as the control shaft position adjusting mechanism, and the driven shaft is rotated by rotating the worm gear by the actuator, thereby rotating the control shaft. A variable valve mechanism failure diagnosis apparatus for an internal combustion engine, characterized by being a mechanism for adjusting a valve characteristic of the internal combustion engine by moving in an axial direction. 4. The variable valve mechanism according to claim 3, further comprising a spiral cam as the control shaft position adjusting mechanism, wherein the control shaft is moved in the axial direction by rotating the spiral cam by the actuator. A mechanism for adjusting valve characteristics, wherein the retractable travelable area is set to an adjustment state in which the valve characteristics are maximized, and the spiral cam is an arc having a cam rotation axis as an axis on a cam surface corresponding to the retractable travelable area Having a surface,
The variable valve mechanism failure diagnosis apparatus for an internal combustion engine, wherein the failure diagnosis means determines the failure of the actuator by driving the actuator toward a direction in which the valve characteristic increases. 4. The variable valve mechanism according to claim 3, comprising a worm gear as the control shaft position adjusting mechanism, and rotating the driven gear by rotating the worm gear by the actuator to move the control shaft in the axial direction. Is a mechanism for adjusting the valve characteristics of the internal combustion engine,
The variable valve mechanism failure diagnosis apparatus for an internal combustion engine, wherein the failure diagnosis means determines the failure of the actuator by driving the actuator toward a direction in which the valve characteristic increases. 10. The failure diagnosis unit according to claim 8, wherein the failure diagnosing means drives the actuator to increase the valve characteristics in an output state at a level lower than a driving force output during normal control of the internal combustion engine. A variable valve mechanism failure diagnosis apparatus for an internal combustion engine. 11. The failure diagnosis unit according to claim 3, wherein when the actuator is normally driven toward a larger valve characteristic, the failure diagnosis means moves the actuator toward a smaller valve characteristic. A variable valve mechanism failure diagnosis apparatus for an internal combustion engine, wherein a failure of the actuator when the valve characteristic is reduced by driving is determined. A control shaft for adjusting one or both of the valve lift amount and the valve operating angle of the internal combustion engine is driven by an actuator through a control shaft position adjusting mechanism, and the valve characteristic by the control shaft is detected by a sensor, A failure diagnosis apparatus for a variable valve mechanism in which the actuator is controlled based on a detection value of the sensor,
A failure diagnosis means for performing a failure diagnosis of the variable valve mechanism when it is determined that the valve characteristic exists in a retreatable travelable region set within the adjustment range of the valve characteristic by the variable valve mechanism;
When the failure diagnosing means diagnoses that the variable valve mechanism is in failure, the holding control for holding the valve characteristic in a state in the retractable travelable region, or the valve than the retractable travelable region. Valve state holding means for performing holding control for holding in a state where characteristics are large;
With
The variable valve mechanism includes a worm gear as the control shaft position adjusting mechanism, and rotates the driven gear by rotating the worm gear by the actuator, thereby moving the control shaft in the axial direction of the internal combustion engine. A mechanism for adjusting the valve characteristics, the retreat travelable region is set to a region larger than the lower limit of the adjustment position of the valve characteristics capable of retreat travel,
The variable valve mechanism failure diagnosis apparatus for an internal combustion engine, wherein the failure diagnosis means determines the failure of the actuator by driving the actuator toward a direction where the valve characteristic becomes smaller. 13. The failure diagnosis unit according to claim 12, wherein the failure diagnosis means increases the valve characteristic by driving the actuator toward a larger valve characteristic when the actuator is normally driven toward a smaller valve characteristic. A variable valve mechanism failure diagnosis apparatus for an internal combustion engine, wherein a failure of the actuator in the case of performing is determined. 14. The start valve characteristic setting means for driving the actuator so that the valve characteristic is in an initial state set for starting when the internal combustion engine is stopped. The variable valve mechanism failure diagnosis apparatus for an internal combustion engine, characterized in that the state is set in the retreatable travelable region.

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